The ethnic-labor hierarchy seen here—white and Asian American US citizen, Latino US citizen or resident, undocumented mestizo Mexican, undocumented indigenous Mexican—is common in North American farming. The relative status of Triqui people below Mixtecos can be understood via a pecking order of perceived indigeneity. For example, many farm workers and managers told me the Triqui are more ‘‘purely indigenous’’ than other groups, Triqui is still their primary language, and ‘‘they are more simple.’’ Ethnicity functions as a camouflage for perceived indigeneity versus civilization. The Anglo and Japanese Americans inhabit the pole of civilization, modernity. The Triqui are positioned as the opposite, indigenous peasants, savages, simpletons. The more modern one is perceived to be, the better one’s job. As illustrated in Figure 3, this hierarchy of modernity also correlates roughly with citizenship from US citizen to US resident=Mexican citizen to undocumented immigrant=Mexican citizen . Yet, this diagram shows only a small piece of the global hierarchy. The continuum of structural vulnerability can be understood as a zoom lens, moving through many such diagrams. When the continuum is seen from furthest away, it becomes clear that the farm owners are near the bottom of the global corporate agribusiness hierarchy. When looked at more closely, garden grow bags we see the hierarchy on this particular farm.Responsibilities, stressors, and privileges differ from the top to the bottom of this hierarchy.
Everyone on the farm is structurally vulnerable, although the characteristics and depth of vulnerability change depending on one’s position within the labor structure. Control decreases and anxieties accumulate as one moves down the pecking order. Those at the top worry about market competition and the weather. The middle managers worry about these factors as well as about how they are treated by their bosses. The pickers also worry about picking the minimum weight in order to avoid losing their job and their housing. The higher one is positioned in the structure, the more control over time one has . The executives and managers can take breaks as their workload and discretion dictate. The administrative assistants and checkers can take short breaks, given their supervisor’s consent or absence. The field workers can take infrequent breaks if they are willing to sacrifice pay, and even then they may be reprimanded. The higher one is located in the hierarchy, the more one is paid. The executives and managers are financially secure with comfortable homes. The administrative staff and checkers are paid minimum wage and live as members of the rural working class in relatively comfortable housing. The pickers are paid piecemeal and live in labor camp shacks. They are constantly aware of the risk of losing even this poor housing. Among pickers, those in strawberries make less money and are more likely to miss the minimum and be fired than those in apples. This segregation is not conscious or willed on the part of the executives or managers. Rather, inequalities and the anxieties they produce are driven by larger structural forces. While farm executives are vulnerable to macro-social structures, vulnerability is further conjugated through ethnicity and citizenship, changing character from the top to the bottom of the labor hierarchy . Bodies are organized according to the social categories of ethnicity and citizenship into superimposed hierarchies of labor possibilities and housing conditions.
The over determination of the adverse lot of indigenous Mexican migrant berry pickers tracks along the health disparities seen throughout the public health literature on migrant workers . The focus on risk and risk behaviors in public health and medicine carries with it a subtle assumption that the genesis of vulnerability and suffering is the individual and his or her choices . This focus often leads to blaming inadvertently the individual victim or their ‘‘culture’’ for their structurally produced suffering . Public health and medical interventions are planned with the goal of changing individual choices, behaviors, and values. The concept of structural vulnerability, on the other hand, refocuses our analysis onto the social structure as the locus of danger, damage, and suffering. Without such a concept, diagnoses and interventions rarely correspond with the context of suffering and may instead comply with the very structures of inequality producing the suffering in the first place . The concept of structural vulnerability is crucial not only to refine anthropological analyses of the social production of suffering but also to reorient medical and public health attention away from individual behaviors and toward social structures.Farmland covers more than 35% of Earth’s ice-free terrestrial area, and agriculture is expanding and intensifying in many regions to meet the growing demands of human populations . This trend threatens biodiversity and the ecosystem services on which agriculture depends, including crop pollination . Indeed, recent reviews have highlighted how multiple anthropogenic pressures lead to a decline in wild pollinators such as bees, flies, beetles, and butterflies . However, practices to enhance wild pollinators in agroecosystems are still in development , and considerable uncertainty remains regarding their effects on crop yield and farmers’ profits.
Here we review recent research on the topic, including the impacts of certain practices on wild pollinators, crop pollination, yield, and profits . We focus on practices that enhance the carrying capacity of habitats for wild insect assemblages that may then provide crop pollination services; practices to conserve or manage a particular pollinator species are outside our scope although they have received attention elsewhere . We offer general science-based advice to land managers and policy makers and highlight knowledge gaps. Throughout, we emphasize the need to consider population-level processes, rather than just short-term behavioral responses of pollinators to floral resources.Plant–pollinator interactions are typically very general, with many pollinators being rewarded with pollen, nectar, or other resources from several plant species , and with most angiosperms being pollinated by multiple insect species . Humans benefit from this generalized nature of pollination systems, as exotic crops brought far from their ancestral ranges can find effective pollinators within native insect assemblages . Accordingly, a synthesis of 600 fields from 41 crop systems showed that only two of the 68 most frequent pollinators globally were specialist species: the weevil Elaeidobius kamerunicus pollinating oil palm and the squash-bee Peponapis pruinosa pollinating pumpkin .Because of differences in species functional traits, greater pollinator richness can lead to foraging complementarity or synergy, improving the quantity and quality of pollination and therefore increasing both the proportion of flowers setting fruits and product quality . Across crop species, insects with contrasting mouth part lengths may be needed for the pollination of flowers not only with easily accessible rewards but also with rewards hidden at the bottom of a tubular corolla . Within a crop species, social and solitary bees visited flowering radish plants at different times of day, suggesting temporal complementarity among these pollinator groups . Flower visiting behavior also differs among pollinators of different body sizes, and visits by a range of differently sized pollinator species increase pumpkin pollination . In addition to functional traits, interspecific differences in response traits to climate and land-use change can increase resilience of pollination services . The role of diverse assemblages of wild insects in crop pollination is also evident from recent global analyses. Worldwide, incomplete and variable animal pollen delivery decreases the growth and stability of yields for pollinator-dependent crops . This lower yield growth has been compensated for by greater land cultivation to sustain production growth . The consequent reduction in natural areas within agricultural landscapes decreases the richness and abundance of wild pollinators, including bees, syrphid flies, and butterflies , further diminishing crop pollination . A possible solution to this “vicious cycle” is to increase pollinator abundance through single-species management, most commonly European honey bees , tomato grow bags which are not greatly affected by isolation from natural areas . However, increasing the abundance of one species may complement but not replace the pollination services provided by diverse assemblages of wild insects, and wild insects pollinate some crops more efficiently than honey bees . Moreover, during the past 50 years, the fraction of animal-pollinator dependent agriculture and the number of managed honey bee hives have increased 300% and 45%, respectively, and honey bees have suffered from major health problems such as colony collapse disorder . All of these factors point to the potential benefit of practices that boost the species richness and abundance of wild pollinators. Indeed, richness and visitation rate of wild pollinators are strongly correlated across agricultural fields globally . Therefore, practices that enhance habitats to promote species richness are also expected to improve the aggregate abundance of pollinators, and vice versa .Below we describe practices that diversify and improve the abundance of resources for wild insects outside the crop field, without affecting crop management. Practices are ranked from less-to-more required area, with practices covering less area likely to be less costly . Nesting resources – such as reed internodes and muddy spots for cavity nesters, and bare ground for soil nesters – can be enhanced at crop field edges without affecting much of the crop area. Although providing such resources can promote the recruitment of certain bee species , evidence of its effects on crop yield is lacking .
Hedgerows and flower strips are woody or herbaceous vegetation, respectively, planted at the edge of a crop field, and generally covering only a small area. If appropriate plant species are chosen and adequately managed through time , hedgerows and flower strips can provide suitable food and nesting resources for, and enhance species richness and abundance of, bees and syrphid flies . These practices also enhance pollinators in adjacent fields – rather than simply concentrating pollinators at dense flower-rich regions – and therefore increase crop yield . Regional programs that augment the quality and availability of seeds from native flowering plants are important for the success of these practices . Conserving or restoring natural areas within landscapes dominated by crops often provides habitat for wild pollinator populations . In addition, pollinators depend on various types of resources , which are difficult to provide in ways other than by enhancing natural areas. Consequently, these areas also enhance pollination services for nearby crops . Enhancing farmland heterogeneity increases pollinator richness because plant species provide complementary resources over time and space, and insect species use different resource combinations . Also, insects usually require resources for periods longer than crop flowering . In fact, a synthesis of 605 fields from 39 crop systems in different biomes found that diversity of habitats within 4 ha enhanced bee abundance by 76% as compared with bee abundance in monoculture fields . Smaller crop fields increase land-use heterogeneity, and also benefit pollinators because most species forage at distances less than 1 km from their nests . Thus, crops in small fields are more likely to benefit from pollinator enhancements such as nearby field margins and hedgerows . Indeed, pollinator richness, visitation rate, and the proportion of flowers setting fruits decreased by 34%, 27%, and 16%, respectively, at 1 km from natural areas across 29 studies worldwide .In contrast to off-field methods that can be ordered from smaller to larger scale , on-field practices are all applied at a similar spatial scale, ie that of the crop field. Here we discuss practices that reduce the use of insecticides and machinery, enhance the richness of flowering plants, and require greater effort because of changes in the crop species or system . Reducing the use of synthetic insecticides that are toxic to pollinating insects should provide an important benefit . For example, in South Africa, insecticides adversely affected pollinators, impairing rather than enhancing mango yield . Insecticides with low toxicity to pollinators, with non-dust formulations, applied locally through integrated pest management practices, and applied during the non-flowering season are less likely to be detrimental to pollinators than highly toxic, systemic insecticides that are broadly sprayed from airplanes . No-tillage farming may enhance populations of ground nesting bees given that many species place their brood cells <30 cm below the surface . Tillage timing, depth, and method probably have differential impacts on pollinators and pollination, but further studies are required to verify this expectation . Similarly, flood irrigation may be detrimental in comparison to drip irrigation because of the increased likelihood of flooding pollinator nests but, particularly in arid systems, irrigation in general can promote wild-insect abundance through higher productivity of flowering plants or by making the soil easier to excavate .